1. Field of the Invention
The present invention relates generally to the field of high frequency antennas, and particularly to dual band, high frequency antennas disposed to exhibit good isolation and good diversity performance in a limited space.
2. Related Art
Wireless networking and, in particular, IEEE-802.11 compatible networking (“WiFi”) has seen explosive growth. As the demand for wireless throughput increases, increasingly more complex methods must be employed to make optimal use of the limited radio frequency (RF) bandwidth. A recent RF technique called Multiple-In, Multiple-Out (MIMO) technology is being standardized as IEEE-802.11n.
MIMO makes use of the different propagation paths between various antennas to transmit a plurality of data streams simultaneously. At least one of a communicating pair of transceivers must be equipped with multiple antennas. To use the MIMO technique effectively, it is advantageous to provide isolation between the multiple antennas. In an access point, for example, substantial physical spacing can be used to separate the antennas. Client devices (e.g. PCMCIA cards used in laptop computers) may, however, lack the physical size needed to achieve meaningful physical antenna separation.
Therefore, a need arises for an apparatus and method that achieves good isolation among multiple antennas disposed in a limited space.